The invention relates to boats which are utilized in the sport of whitewater boating, and more particularly to kayaks which can be adjusted in the volume of their hull for performing water acrobatics in whitewater.
Recently, the sport of water acrobatics has been developed in whitewater boating, particularly in kayaks. Boaters haved foud that the eddy currents in a river can be used with the bow or stern end of the hull partially sunk to do front and rear end stands, spins, and other type acrobatics in the water. For example, a kayak with its stern end submerged may be made to spin under the influence of side eddy currents. Once the spinning is started, the speed can be increased or decreased by the boater moving his hip back or forth. By utilizing subtle movements and paddling strokes, the spinning can be maintained.
The problem occurs that a kayak whose hull prescribes a fixed volume is suitable for water acrobatics for persons in a narrow weight range. A certain amount of weight is required to sink the bow or stern of the kayak hull. If a person is too light, the stern or bow portions will not be sufficiently sinkable for water acrobatics. The problem is basically one of volume versus weight. A decrease in the volume of the stern would render the hull sinkable by a lighter person.
Thus it is highly desirable to be able to vary the volume of the hull of a kayak so that the kayak may be tailored to the weight of a person for acrobatics in whitewater.
U.S. Pat. No. 2,612,129 discloses adjusting the keel of a boat hull for different power levels. In U.S. Pat. No. 4,480,579, issued to the applicant, a kayak with an adjustable rocker is disclosed providing a desired maneuverability depending on the whitewater conditions. This is highly desirable in order to adjust the kayak in different water conditions. However, none of the above teach varying hull volume to render the hull sinkable for water acrobatics.
Accordingly, an object of this invention is to provide a kayak whose hull may be adjusted in volume to render it sinkable over a wide range of boater's weight for the performance of water acrobatics.
Still another object of the invention is to provide a kayak whose hull can be adjusted in its volume without adding significant weight to the hull.
Another object of the present invention is to provide a kayak employing light-weight structure in a hull section by which volume changes in the hull section may be accomplished for water acrobatics in a manner which is simple and easily done by an average boater.